Chronic effects of ethanol under partial inhibition of catalase activity in the rat heart: Light and electron microscopic observations

In order to test the hypothesis that cardiac catalase plays a protective role in the pathogenesis of alcoholic cardiomyopathy, ethanol, comprising 36% of dietary calories, was administered to the rats for 5 weeks under inhibited cardiac catalase activity. Rats were treated with 3-amino-1,2,4-triazole (AT), a specific enzyme inhibitor, or iso-osmotic saline as control. During ethanol feeding, cardiac catalase activity was significantly inhibited at 24 h after AT, 25.6 ± 4.7 IU/mg protein, compared to rats given isoosmotic saline, 51.0 ± 9.1 IU/mg protein (s.d.m.) (P < 0.001). Under light microscopy, observed were intrasarcoplasmic vacuolization and occasional foci of necrosis and fibrosis. Ultrastructural abnormalities included very extensive vesicular changes in the myocardial cells, abnormally increased interstitial fibrosis, dilatation of tubular structures of sarcoplasmic reticulum, increased numbers of lysosomes, dehiscence of intercalated disc and various mitochondrial alterations including amorphous inclusion body. None of the rats given ethanol + saline, pair-fed diet + AT or saline showed comparable changes. Thus, cardiac catalase is considered to play a metabolic and protective role in the rat myocardium chronically exposed to ethanol.